Spalted wood occurs naturally in forests in felled logs and trees which have been infected with spalt fungus (a combination of white rot and blue stain). The spalting makes the wood brittle and difficult to cut into lumber. Therefore, it has not been possible to cut the spalted wood into veneers.
According to the American National Standards Institute, a veneer is a thin sheet of wood, rotary cut, sliced, or sawed from a log, bolt or flitch. A veneer is referred to as a ply when assembled. The formation of spalted veneers would permit the manufacture of spalted engineered wood flooring having a spalted wood veneer decorative layer.
Naturally occurring spalted maple is traditionally used by artisans in lathe produced turnings, e.g. bowls and vases. While spalted solid wood floors have been made from lumber pieces cut from spalted logs, it has not been possible to cut the spalted logs into veneers for use in making engineered wood and engineered wood floors. If the decay progresses too far, the wood becomes punky, soft and spongy, stringy, ringshaked, pitted or crumbly.
Spalting is a decay process in certain wood species that gives the wood a unique blotchy appearance having dark lines. White rot is a decay mechanism that yields thin distinctive lines with broad lighter colored areas in between the lines. White rot is caused by white rot decay fungi. The white rot attacks the cellulose and lignin giving the wood a whitish appearance and multicolored streaks of black, pink and gray. The white rot spores are typically airborne.
Blue stain does not contribute to the decay of the wood but does yield a yellow, orange, red, blue, black or brown coloration. It is caused by microscopic fungi that infect only the sapwood. The blue stain fungi are normally spread by spores that are carried into the wood by insects.